1. Field of the Invention:
The present invention relates generally to exercise devices and, more particularly, to a microprocessor controlled electro-hydraulic exercise system which automatically provides resistance according to individual user strength input.
2. Description of Related Art:
Various exercise devices have been developed over the past number of years which have raised the level of sophistication associated with lifting weights. Even so, the problem of selecting an appropriate weight for the individual user through guesswork or trial and error still remains, as does the associated inconvenience of having to manually select such weight through placement of selector pins, adjusting knobs and dials, or the like. Other exercise devices utilize various configurations of keypads, keyboards, or control panels.
Further, while accomodating resistance has been known in the art for some time, it has only been addressed by applying isokinetics, or constant velocity, through various mechanical, electrical, or hydraulic designs. Other common modes of resistance, such as isotonics (or constant force) have also been available. However, these modes of resistance have never been combined in order to take advantage of their desirable characteristics, and have only recently been provided as alternative modes of operation in a single exercise device.
U.S. Pat. No. 4,354,676, to Ariel, concerns an exercise machine having an exercise bar supported for rotation. This exercise bar acts against a hydraulic cylinder when it is rotated, with the angle of the bar and the pressure in the cylinder simultaneously measured during exercise. This data is fed to a microcomputer which indirectly controls the cylinder pressure through an adjustment in the position of a control valve in accordance with a selected exercise program. Additionally, the microcomputer provides outputs to displays which enable the person exercising to monitor his progress. The alleged improvement of the Ariel device over the prior art involved the measurement of force applied to the exercise bar and the angular displacement of the bar so that stored values for variables such as force, velocity, or acceleration can be compared with the measured values to develop a control signal for the hydraulic cylinder in order to ensure that the measured output values equal the desired values.
U.S. Pat. No. 4,544,154, to Ariel, is a continuation-in-part patent of the '676 patent, and relates to a passive programmable resistance device which utilizes a closed loop feedback system for controlling resistance to rotational or translational motion of an object. One or more actual parameters, such as force or position, are measured and compared with desired parameters, with the differences therebetween used to provide a control signal which controls the resistance to the movement of the object.
While the devices disclosed by the Ariel '676 and '154 patents recognize the need for regulating various parameters associated with lifting weights in order to provide what has become known in the industry as "accommodating resistance", or resistance conforming to user effort, these devices require a closed loop feedback to be implemented into the microcomputer software to maintain constant control parameters. This type of design is not only costly in terms of expense and microcomputer memory, but is complex in its application as well. Deviations from the constant control parameter must be detected by the software and then remedied by controlling a valve in order to provide compensating restriction to the flow of hydraulic fluid, thereby providing more or less resistance.
The other option which is provided in the Ariel devices is a mode of operation wherein a preprogrammed routine for force, velocity, or acceleration is utilized. This makes variable resistance available to the user pursuant to a known performance curve, even though it is not an accomodating resistance. Shortcomings of this mode of operation include the fact that the preprogrammed routine is either not specifically tailored to the user's needs, does not reflect the user's strength level at the time of exercise, or causes him to undergo the time consuming inconvenience of establishing a customized routine.
Thus, heretofore, there has not been provided in the industry an exercise device which automatically provides accomodating resistance at all phases of the exercise, including the determination of the appropriate amount of resistance at the beginning of the exercise, in a relatively simple and economical fashion.